90Y is a radioisotope for medical treatment and is being used clinically. As the use of 90Y is getting increased, various types of generator systems have been developed over the last years.
However, currently, most of the registered patents are process patents such as solvent extraction processes by using metallic complexing agents, separation processes using commonly-used adsorbents, and the like.
Referring to the conventional technologies, Korean Patent Registration No. 3034 discloses an yttrium separation method, in which an aqueous mineral acid solution and a solution in which an yttrium-containing mixture dissolves in at least one of an organic acid solvent and an organic phosphate solvent flowing in the opposite direction are brought into contact with each other through a multistage liquid-liquid extraction system to extract a solute, and then the extracted solute returns to the first stage of the multistage liquid-liquid extraction system and thus the counterflow and contact procedure is further performed to recover an yttrium-containing solution, and then the recovered yttrium-containing solution is mixed with other solvents (among these solvents, at least one is different from the first solvent) to form mixed solutions, and then these mixed solutions flow in opposite directions and are thus brought into contact with each other through the multistage liquid-liquid extraction system to extract a solute, and then the extracted solute further returns to the first stage of the multistage liquid-liquid extraction system, thereby separating a pure yttrium-containing solution.
U.S. Patent Application Publication No. 2006-0018813 discloses a method for purifying 90Y from 90Sr, comprising the steps of: (a) dissolving a radioactive strontium nitrate salt including 90Sr nitrate and 90Y nitrate in a water solution to form a mixed solution; (b) evaporating and then primarily drying the mixed solution to leave solids; (c) contacting the solids with more than 80 wt % of nitric acid (HNO3), whereby 90Y is dissolved in the acid solution and strontium is precipitated as a solid; and (d) separating the solids from the acid solution containing the 90Y, thereby purifying the 90Y.
However, the above solvent extraction processes are problematic in that a large amount of radioactive organic wastes is generated.
Therefore, recently, adsorption processes have been largely used to separate yttrium, And technologies of obtaining a final 90Y solution having a ratio of 90Sr/90Y of about 10−5−10−8 using a two, three, or more column stages have also been developed. In particular, since 90Sr has a half-life period of 28.8 years and accumulates in bones when it is absorbed in a human body, it is a radioactive isotope whose content is strictly limited to 20 μCi per 1 Ci 90Y solution.
U.S. Patent Application Publication No. 2004-0005272 discloses a method of separating 90Y from 90Sr, comprising: adsorbing 90Sr onto an inorganic ion exchange material from an aqueous solution including a source of 90Sr; and eluting 90Y from the inorganic ion exchange material with a solution having a pH greater than about 5 and including a chelating agent.
U.S. Patent Application Publication No. 2004-0164025 discloses a method for separating metallic elements in aqueous solution using a hydrophobic chelating extractant, such as an organophosphorus compound, adsorbed onto carbon or graphite fibers in the form of felt, and discloses a 90Y generator system including two extraction columns designed to selectively absorb 90Y at different pHs.
However, when such an inorganic ion exchange material or a solvent extractant such as a hydrophobic chelating extractant is used, there is a problem in that organic matter gets decomposed by radiation and poisonous matter is released along with 90Y.
Therefore, the present inventors have made efforts to realize a system for producing a 90Y solution through a simple process without generating poisonous matter that is harmful to a human body. As a result, it is found that since an adsorbent, prepared by introducing a bifunctional organosilane compound, such as a phosphonic group into silica which is the bone structure of the adsorbent, has a very low affinity to 90Sr and a very high affinity to 90Y. By composing the adsorbent through the provided scheme here and the uses as a column material, high-purity 90Y can be produced even when a one-stage adsorption column is used. Based on these findings, the present invention was completed.